a leaf warbler's gleanings

A new class of insecticides based on nicotinoids seem to be the key factor underlying the widely reported declines in house sparrows and other birds as well as the alarming colony collapse disorder in honeybees, according to a new book "The systemic insecticides: a disaster in the making" by Dutch cancer biologist Henk Tennekes. Is this our generation's "Silent Spring"? Perhaps - we'll have to read the book to dig into the specific details. I have to say though, that the wide use of apparently broad-spectrum insecticides seems like a far more plausible cause of such widespread declines in bees and insect-dependent birds than cellphone towers or a litany of other local factors that have been suggested, unconvincingly. What strengthen's the case is that neonicotinoids apparently make bee colonies more susceptible to the combination fungal/viral infections that have recently been implicated in colony collapse! Here's an excerpt from today's article in the Independent raising the alarm on this:

Scanning the sky with his binoculars, he searches carefully for any sign of movement: the steady beat of a blackbird's wings, the fluttering of a flock of starlings. It has been a week now since he saw the starlings: just four of them flitting from tree to tree, feasting on the autumn berries.

Birds are a real rarity these days. In his boyhood, he recalls, he would watch the acrobatics of entire flocks as they ducked and dived after insects. But now the skies are silent, barring the hum of the odd airplane. Turning back to his fruit and vegetable patch, he continues the laborious task of pollinating the raspberry plants by hand, gently brushing pollen onto the slender stigmas inside the flowers. In the past, bees, wasps, butterflies and flies would have done this job for him; nowadays such insects are likewise a rarity. Farmers instead resort to robot bees to pollinate their crops: tiny motors, encased in fuzzy fabric, which hover from flower to flower.

Will this bleak outlook be a reality for future generations? It is nearly 50 years since Rachel Carson wrote Silent Spring, the book that warned of environmental damage the pesticide DDT was causing. Today, DDT use is banned except in exceptional circumstances, yet we still don't seem to have taken on board Carson's fundamental message.

According to Henk Tennekes, a researcher at the Experimental Toxicology Services in Zutphen, the Netherlands, the threat of DDT has been superseded by a relatively new class of insecticide, known as the neonicotinoids. In his book The Systemic Insecticides: A Disaster in the Making, published this month, Tennekes draws all the evidence together, to make the case that neonicotinoids are causing a catastrophe in the insect world, which is having a knock-on effect for many of our birds.

Already, in many areas, the skies are much quieter than they used to be. All over Europe, many species of bird have suffered a population crash. Spotting a house sparrow, common swift or a flock of starlings used to be unremarkable, but today they are a more of an unusual sight. Since 1977, Britain's house-sparrow population has shrunk by 68 per cent.

The common swift has suffered a 41 per cent fall in numbers since 1994, and the starling 26 per cent. The story is similar for woodland birds (such as the spotted flycatcher, willow tit and wood warbler), and farmland birds (including the northern lapwing, snipe, curlew, redshank and song thrush).

Ornithologists have been trying desperately to work out what is behind these rapid declines. Urban development, hermetically sealed houses and barns, designer gardens and changing farming> practices have all been blamed, but exactly why these birds have fallen from the skies is still largely unexplained.

However, Tennekes thinks there may be a simple reason. "The evidence shows that the bird species suffering massive decline since the 1990s rely on insects for their diet," he says. He believes that the insect world is no longer thriving, and that birds that feed on insects are short on food.

So what has happened to all the insects? In the Nineties, a new class of insecticide – the neonicotinoids – was introduced. Beekeepers were the first people to notice a problem, as their bees began to desert their hives and die, a phenomenon known as Colony Collapse Disorder (CCD).

[via Common Dreams]